25826-75-9Relevant articles and documents
Metal-free, one-pot, sequential protocol for transforming ,-epoxy ketones to -hydroxy ketones and -methylene ketones
Hasegawa, Eietsu,Arai, Saki,Tayama, Eiji,Iwamoto, Hajime
, p. 1593 - 1600 (2015/02/19)
A new sequential, one-pot protocol for transforming 1,3-disubstituted 2,3-epoxy ketones to β;-hydroxy ketones and α-methylene ketones has been developed. Reaction of epoxy ketones with boron trifluoride etherate (BF3·OEt2) generates the cationic intermediates by regioselective epoxide ring opening and an acyl shift. Then, a treatment of these cations with 2-aryl-1,3-dimethylbenzimidazolines (DMBIH) results in formation of 1,2-disubstituted 3-hydroxy ketones. DMBIH serves as a hydride donor in the second step of this process. Finally, the β;-hydroxy ketones can be converted to 1,2-disubstituted 2-methylene ketones by treatment with methanesulfonic acid or a combination of methanesulfonyl chloride and triethylamine. Importantly, the sequential steps involved in formation of the α-methylene ketone products can be carried out in one pot.
Selective Cβ-O Bond Cleavage of Chalcone Epoxides Induced by Pyrylium Salt Sensitized Photoreactions and Dark Reactions with Cerium(IV) Salts
Hasegawa, Eietsu,Ishiyama, Kenyuki,Kashiwazaki, Hiroki,Horaguchi, Takaaki,Shimizu, Takahachi
, p. 4045 - 4048 (2007/10/02)
The Cβ-O bonds of chalcone epoxides (1a, 1b) were selectively cleaved by pyrylium salt sensitized photoreactions, affording β-ketoaldehydes (2a, 2b) in CH2Cl2 and MeOH-adducts (3a, 3b) in MeOH.Similarly, cerium(IV) salts catalyzed the MeOH-adduct formations of 1a and 1b in the dark.On the other hand, nitrate ester (4b) was obtained on treatment of 1b with a cerium(IV) salt in MeCN.